The purposes of this research are to describe patterns of confusion development and to identify those factors related to the development of acute confusion and adverse functional changes in the hospitalized elderly. The study has three specific aims: to describe patterns of confusion development; to explore the relationship of interactive factors involving vital function, autonomic stability, sensory-motor function, and environmental factors to the development of confusion; and to describe early cues/cue clusters that can be identified through nursing assessment which precede the development of confusion. Acute confusion behavior is considered an extreme manifestation of a spectrum of non-adaptive psychophysiological responses which involve disturbed internal-external information processing. The patterns of development of confusion, their manifestations and their responsiveness to interventions depend on the interaction of etiological factors over time and variations in individuals with different vulnerability. An understanding of patterns of confusion development and identification of factors contributing to the development of confusion are prerequisites to early nursing diagnosis and effective intervention and/or prevention. Using an interactive factor framework to describe disturbed information processing, this study uses a descriptive, time-series, repeated measures design to explore the relationship of five factor variables -- oxygenation status, nutritional status, autonomic stability, activity/sensory-motor level, and environmental interactive factors -- to the development of acute confusion and adverse functional changes in the hospitalized elderly. Data will be collected on 225 elderly subjects admitted to the general medical services in a large teaching and referral hospital. Physiological measurements, standard instruments and structured interviews will be employed. The ultimate goal is to identify risk factors and predictors of confusion development which would facilitate early nursing diagnosis and intervention to reduce the occurrence and consequences of confusion in the hospitalized elderly.